Test characteristics of common appendicitis scores with and without laboratory investigations: a prospective observational study

BACKGROUND: Despite the poor independent test characteristics of the white blood cell count (WBC) and neutrophil count (NC) in identifying appendicitis, common clinical decision supports including the Pediatric Appendicitis Score (PAS) and Alvarado Score (AS), require the WBC and NC values. Moreover, blood tests cause discomfort/pain to children and require time for processing results. Scores based on clinical information alone may be of benefit in the pediatric population. The objective of our study was to determine the test characteristics of the PAS and the AS with and without laboratory investigations (mPAS, mAS respectively) as well as the Lintula Score. METHODS: A prospective cohort study of children aged 5–17 years presenting to a pediatric ED with suspected appendicitis. Clinical care of the patient was left to the managing physician. At risk for appendicitis was defined by PAS ≥6; AS ≥5; LS ≥16, as originally described; modified cutoffs were defined as mPAS ≥4; mAS ≥4. Appendicitis was defined as acute inflammation, rupture or abscess of the appendix on pathologic evaluation. Test characteristics for each of the 5 scores were calculated. RESULTS: Of the 180 eligible children, 102 (56.7 %) were female. The average age was 11.2 years (SD 3.1). Appendectomy was performed in 58 (32.2 %) of children, 55 (94.8 %) were positive. For the PAS and mPAS, sensitivity and negative predictive values were similar (80.0 %, 86.4 % vs 87.3 %, 85.1 % respectively). For the AS and mAS, sensitivity and negative predictive values were also similar (85.5 %, 87.1 % vs 83.6 %, 83.3 % respectively). Specificities in the PAS, mPAS, AS and mAS were low (56.0 %, 32.0 %, 43.2 %, 63.0 % respectively). Test characteristics of the LS were poor (59.3 %, 79.2 %, 55.2 %, 81.8 %). CONCLUSIONS: A modified Alvarado and PAS can be used to screen for children at low risk of appendicitis who may be carefully observed at home without the need for laboratory investigation. Translation to primary care settings should evaluate generalizability and determine impact on referral patterns. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12887-016-0687-6) contains supplementary material, which is available to authorized users.